Emmerich said that the sequels would be set 20 years after the original film, in a parallel universe-style Earth that has rebuilt in the wake of alien attacks that saw the destruction of cities around the globe -- most notably our nation's capital, in the iconic scene where a hovering alien spaceship blows the White House to bits. While Earth has tried to move on, its citizens are also bracing for the aliens' return, since a distress call sent out by the first group of attackers has just reached its target and more aliens are headed toward our planet.

"The humans knew that one day the aliens would come back," Emmerich said. "And they know that the only way you can really travel in space is through wormholes. So for the aliens, it could take two or three weeks, but for us that's 20 or 25 years."

In the mean time, Emmerich said humans have been able to harness some of the aliens' technology.

"We don't know how to duplicate it because it's organically grown technology, but we know how to take an anti-gravity device and put it in a human airplane," he said.

The plan is to end the first sequel on a cliff-hanger to keep audiences on the hook for the second film, and Emmerich said both movies will bring back some characters from the original "Independence Day," while also focusing on a new generation of heroes. Bill Pullman, who played the president, has confirmed his return, although there's no word yet from star Will Smith. Emmerich said that some of the action would center on Smith's stepson from the first film, played by Ross Bagley.